“I have been following the Royal Tour but can someone explain to me how Meghan’s baby bump gotten bigger with a few days,” one user wrote on Twitter.

“I also note that Meghan’s baby bump is getting bigger by the day!” agreed Emily Andrews, royal correspondent for The Sun. “I swear it was not this big last week! I think it’s the clinging nature of the dress but she’s sure looking swell!”

So what’s going on? Has Meghan’s baby bump miraculously grown overnight? Is she further along in her pregnancy than the reported three or four months she’s said to be?

It is possible that the shape and fabric of Meghan’s various outfits could have an impact on how large her bump appears and the fact she is holding her stomach in certain pictures could also accentuate its size.

But there’s another reason the Duchess’ bump may have looked particularly pronounced that evening and then almost flat again the following morning.

According to Liz Halliday, Deputy Head of Midwifery at Private Midwivesbaby bumps can actually appear larger at certain times of the day.

“It’s very common for a baby bump to appear more pronounced over the course of the day,” she explains.

Holding your bump can make it seem more pronounced [Photo: Getty]

Speaking to Yahoo UK Liz explained that there are several reasons bump size can appear larger in the evening.

One of those factors is the abdominal muscles.

“The tone of abdominal muscles decreases over the course of the day and so a woman’s bump may appear smaller in the morning when the muscles are rested and larger as the day progresses and the muscles become tired and offer less support,” Liz explains.

Bloating is another consideration. “As the day progresses and we eat more food, the bowel becomes fuller leading to a more pronounced bump,” Liz continues.

“Hydration also plays a role here as early in the morning we are less hydrated having been asleep and therefore not consuming water. Throughout the day we consume water and this can cause some bloating, not to mention a full bladder, which will push the uterus upwards, creating a larger bump,” she adds.

The other factor that could be at play is Meghan’s hormones. “Progesterone causes a slowing of gut motility making the above-mentioned bloating more pronounced in pregnancy than in non-pregnant people,” Liz explains.

So are all pregnant women prone to the growing then disappearing bump phenomenon?

“The degree to which a woman may experience this is very individual and may be influenced by pre-pregnancy weight, fitness level, core strength, age and how many pregnancies she has carried,” Liz explains.

Click below for Meghan’s complete tour wardrobe:

Liz Halliday also believes that the stage of pregnancy Meghan is rumoured to be in (four months) could mean we see her bump size appearing to alter quite rapidly, over the course of the next few weeks and indeed the remainder of the royal tour.

“At 12 weeks the top of the uterus is located just above the pelvic bone and continues to grow weekly during pregnancy,” she says.

“With only one week of the royal tour left Meghan’s bump is unlikely to change noticeably within this time. More dramatic changes to the size of the bump can be expected in the third trimester when the baby is putting on weight.”

The Duchess isn’t the only celebrity to be subject to scrutiny over her bump size. Back when Beyonce was pregnant with Blue Ivy, rumours were sparked that the singer was wearing a prosthetic belly after her stomach appeared to collapse as she sat down during a live TV appearance in Australia.